Welcome to Medical News Today

Healthline Media, Inc. would like to process and share personal data (e.g., mobile ad id) and data about your use of our site (e.g., content interests) with our third party partners (see a current list) using cookies and similar automatic collection tools in order to a) personalize content and/or offers on our site or other sites, b) communicate with you upon request, and/or c) for additional reasons upon notice and, when applicable, with your consent.

Healthline Media, Inc. is based in and operates this site from the United States. Any data you provide will be primarily stored and processed in the United States, pursuant to the laws of the United States, which may provide lesser privacy protections than European Economic Area countries.

By clicking “accept” below, you acknowledge and grant your consent for these activities unless and until you withdraw your consent using our rights request form. Learn more in our Privacy Policy.

Please accept our privacy terms

We use cookies and similar technologies to improve your browsing experience, personalize content and offers, show targeted ads, analyze traffic, and better understand you. We may share your information with third-party partners for marketing purposes. To learn more and make choices about data use, visit our Advertising Policy and Privacy Policy. By clicking “Accept and Continue” below, (1) you consent to these activities unless and until you withdraw your consent using our rights request form, and (2) you consent to allow your data to be transferred, processed, and stored in the United States.

Light therapy, or phototherapy, can improve the symptoms of psoriasis in many people. Light therapy works by reducing skin inflammation and slowing down the production of skin cells.

Doctors may recommend light therapy when a person has moderate to severe psoriasis, or psoriasis that has not responded to other treatments.

Along with its benefits, however, light therapy has side effects. Repeated and long-term exposure to light therapy can increase a person's risk of skin cancer.

In this article, we take a close look at light therapy for psoriasis, including its types, effectiveness, and possible side effects.

What is light therapy for psoriasis?

Light therapy can treat psoriasis but will not cure it.

Light therapy involves shining ultraviolet (UV) light on the skin, which can reduce the size, itchiness, and appearance of plaques. It may even clear them up entirely.

Light therapy does not cure psoriasis, but it can help people manage their condition and improve their quality of life.

Light therapy for psoriasis works by slowing down the excess growth of skin cells, which reduces plaque formation. It also limits the growth of skin cells by affecting the functioning of the DNA.

Light therapy procedure

Depending on which areas the psoriasis affects, a person can get phototherapy on one area, such as the hands or scalp, or across their whole body. A healthcare professional will protect sensitive skin areas, such as the eyes and genitals, before treatment.

Light therapy requires multiple sessions to gradually increase the amount of time the skin is exposed to UV light, and to give it time to heal.

People usually undergo three to five light therapy sessions per week over the course of 2–3 months. People usually see an improvement in 2–4 weeks, depending on the type of light therapy.

Each person's skin reacts to phototherapy differently, both in how much improvement they see in their psoriasis symptoms and in how long those benefits last. The average remission time is 3–12 months.

Because of the increased risk of skin cancer, doctors advise people to limit their lifetime usage of psoralen and ultraviolet A (PUVA) phototherapy to 150 sessions.

Is light therapy effective?

Light therapy is effective for reducing or clearing up the symptoms of psoriasis.

An estimated 75 percent of people using narrow-band ultraviolet B (UVB) therapy, which is the most common type, will develop clear skin. This will last for at least 6 months.

Research has found that narrow-band UVB treatments are effective against a rarer form of psoriasis called acute guttate psoriasis, and that people were satisfied with this treatment.

Types of light therapy

The best phototherapy method will depend on which body parts psoriasis affects.

There are many different ways to deliver light therapy for psoriasis, including different types of light and equipment.

A healthcare professional will choose which phototherapy method to use based on the following factors:

how much of the body the psoriasis affects

which body parts psoriasis affects

how much psoriasis affects an individual's quality of life

a person's overall health

a person's skin type

One key difference between the various forms of phototherapy is the type of UV light used in treatment:

UVA has a long wavelength. It can go through glass windows and penetrate to deeper levels of the skin. People must use UVA treatments in combination with psoralen, which makes the skin more receptive to the UVA rays.

UVB has a shorter wavelength. It only reaches the upper levels of the skin and does not require psoralen.

Narrow-band UVB. Narrow-band phototherapy, the most common light therapy, limits the light wavelengths used in treatment to 311–313 nanometers, to keep possible side effects in check.

Broad-band UVB. Broad-band phototherapy is the oldest form of light therapy for psoriasis. It uses a wider wavelength than narrow-band therapy.

Laser UVB. Laser techniques use a smaller, more targeted beam of UVB. Healthcare professionals prefer this technique when psoriasis affects less than 5 percent of the body.

Topical PUVA. With PUVA, a person either soaks in a bath or applies a lotion containing psoralen, which makes the skin more receptive to the UV light treatment that follows.

Oral PUVA. With oral PUVA, a person takes pills containing psoralen before phototherapy. This form of treatment may be especially helpful for very thick plaques.

Pulsed dye laser (PDL). Healthcare professionals most often use PDL for small lesions on the surface of the skin or nail psoriasis.

Balneophototherapy. Here, a person will undergo UV light treatments either while bathing in a salt-based solution or immediately afterward.

Low-level light or laser therapy. Sometimes called "cold laser" treatment, doctors also recommend this treatment for other forms of inflammation and chronic pain.

UVB phototherapy at home. Physicians may prescribe at-home follow-up treatment, with individuals using hand-held or smaller-scale light boxes to stay on top of their psoriasis and manage any increases in itchiness and plaques, or "flares."

Who should get light therapy?

A doctor or skin specialist, called a dermatologist, may recommend light therapy if creams and lotions are not enough to control psoriasis symptoms.

People with moderate to severe psoriasis may benefit from light therapy. In moderate psoriasis, the condition affects 3–10 percent of the body, while severe psoriasis affects more than 10 percent of the body.

People who take medications and over-the-counter supplements that make their skin more sensitive to UV radiation should not undergo phototherapy.

These photosensitizing medications include:

antihistamines

contraceptives

diuretics

sulfa drugs

Talk to a healthcare professional about any current supplements or medications before agreeing on phototherapy.

Pregnant women should avoid light therapy for psoriasis, as should people with:

2019 Healthline Media UK Ltd. All rights reserved. MNT is the registered trade mark of Healthline Media. Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a healthcare professional.